Valmont describes, in Letter Seventy-six, his arrival on the scene at Madame de Rosemonde's estate as operatic: "In fact I dropped from the clouds, like a god in an opera who comes down to unravel the plot" ("En effet, je tombai des nues, comme une Divinité d'Opéra qui vient faire un dénouement"). Opera held an important place in daily life in the 18th century. Here, the opera is present beneath the form of a metaphor. Stagings of operas in the 18th century frequently used mechanized devices to introduce characters at the conclusion of the piece. Ingenuity and artifice were often simultaneously present in the opera, just as they are present in the complex stagings and correspondences of the society depicted in Dangerous Liaisons.
There are two different ways in which the theme of class is brought up in Dangerous Liaisons. Class can only be discussed when there is a difference in class. For example, Merteuil never feels compelled to mention to Valmont how interesting it is that he is an aristocrat. As a result, class is discussed in relation to the servant class and in relation to the bourgeoisie. Servants know everything that goes on in the house where they serve, and yet this knowledge seldom seems to work to their advantage. The Marquise de Merteuil, for example, secured the loyalty of her maidservant, Victoire, by arranging for her to be sent to jail and then rescuing her. If Victoire ever does something to annoy the Marquise, she will very quickly find herself in the slammer again. The aristocracy's mission to make dependency a one-way street, since it has all the power and the lower classes depend on it, seems to be failing when it comes to the middle class. This is on account of a new kind money, which is not attached to land or to inheritance, and which can be used to purchase those privileges which were previously due by default to the aristocracy. For example, the courtesan Emilie is almost purchased by a bourgeois man before Valmont comes a-courting. Luckily, Valmont's old-fashioned aristo-sleaze continues to take precedence over cold, hard cash.
After she is jilted by Valmont, the Présidente de Tourvel is in correspondence with Madame de Rosemonde, whose rheumatism often prevents her from writing her own letters. Madame de Rosemonde writes (Letter One hundred and Twenty-six) that, ill as she is, she herself will serve as Tourvel's doctor ("Médecin") during this period of grief over love. It is interesting that Rosemonde does not offer herself up as confessor or comforter. The suggestion that love is a sickness proves so convincing that soon Tourvel will indeed die of love for Valmont. What Valmont sought to describe as a kind of religious devotion or sacrifice, Madame de Rosemonde wishes Tourvel to view as an indisposition. In fact, Valmont himself claimed to be indisposed when the Présidente refused to see him or accept his love. Illness is also the final punishment of the Marquise de Merteuil. As certain witty members of society remark, sickness reveals the true ugliness of the Marquise's soul.